Careful with that... you get what you pay for. It's not like a Miata... if you buy a race-prepped Miata, pretty much as long as they didn't butcher the cage install and it hasn't been wrecked you can fix or replace anything else on the car pretty readily without a lot of money or time investment.

If you go with a more "race car" type of race car, especially a home-built one, there's a lot more that can go wrong. The worst part is probably just that unlike a production car, you might not have a service manual to refer to!

If you want to go open-wheel or other "kit" car, stick with the known entities. The Stalker is a good platform, all GM parts (LS V8 if you want it, but the V6 is plenty IMO... the car only weighs about 1200 pounds!). Something like a Factory 5 Cobra would be good. Or even one of the popular Miata-based "locost" Lotus clones. But, with any of them, you're dealing with a kit car, so you need to be sure that it was well-built.

So much depends on what your intentions are, though. Casual track days? Casual racing? (don't care if you win, as long as you get the chance to dice it up with somebody) Serious racing? (win! win! win!)

Your choices matter a little more if you're out to win, as you have to choose a club or series to race in, then choose a class, and then choose a car that can be competitive... and prepare it competitively. For casual stuff, all you really have to do is please yourself and your wallet.